Frequently Asked Questions — Technical Support

The standard M3 mounting thread pitch used to secure encased SynQor power modules is 0.5p (defined as M3 x 0.5p). SynQor datasheets permit designers to specify encased baseplate options with either metric threaded inserts or non-threaded pass-through clearance holes. When M3 is specified on any technical drawing or datasheet, the metric fine thread pitch of 0.5 mm per thread is strictly applied.

Significant thermal transfer gains are achieved by optimizing host printed circuit boards to sink heat away from converter pins. Key recommendations include:

• Solder Fillet & Barrel Fill: Ensure a smooth, continuous solder fillet and complete plated-through-hole (PTH) barrel fill to minimize interface thermal resistance.
• Inner Layer Thermal Relief: Utilize 'spoke wheel' thermal relief pads on inner copper layers during hand or wave soldering to prevent excessive heat sinking away from the joint during processing. Note that encased SynQor modules are not compatible with reflow soldering profiles.
• Thermal Vias & Copper Planes: Employ heavy copper weights and large power/ground planes. Place a high density of thermal vias around and beneath the power module to conduct heat across FR4 layers to outer air streams.

SynQor strongly advises direct wave or hand soldering for production units to guarantee maximum electrical conductivity, long-term gas-tight joint reliability, and minimal thermal degradation. While pin sockets are convenient for prototype fixtures and evaluation boards, they introduce contact resistance and high thermal impedance. If production designs require sockets, select tin-plated contacts with high contact normal force to prevent fretting corrosion during thermal cycling or vibration.

Achieving system-level EMI compliance involves coordinated layout, filtering, and grounding architecture:

• Matched Filter Selection: Pair converters with corresponding SynQor AC or DC line filters rated for full input voltage and current requirements. Filter attenuation curves are tailored to converter switching frequencies.
• Differential & Common Mode Filtering: Add differential ceramic capacitors close to module pins for differential noise, and connect common-mode (Y-caps) capacitors through low-impedance paths to chassis ground.
• Physical Separation: Keep filter output terminals and converter input traces as short as possible, isolating clean input lines from noisy output cabling to prevent high-frequency coupling.
• Baseplate Grounding: Connect module metal baseplates directly to chassis ground to provide a deterministic path for circulating common-mode currents.

Multiple DC-DC converters can share a single line filter provided the combined worst-case input current does not exceed the continuous rating of the filter module. A single shared filter is mandatory when paralleling non-isolated modules or sharing current signals referenced to the primary return. Dedicated filters per converter are acceptable when primary side control loops remain completely isolated.

Conducted noise mechanisms can be identified using an RF current probe and spectrum analyzer:

• Parallel Conductor Test: Pass both power leads in the same direction through the current probe. Common-mode noise currents reinforce each other, producing higher spectrum peaks.
• Opposing Loop Test: Loop one lead back through the probe in the opposite direction. Differential-mode noise currents reinforce while common-mode currents cancel out. Comparing noise levels pinpoints the dominant emission mechanism.

SynQor open-frame modules exhibit near-field radiation levels comparable to—or lower than—conventional metal-cased converters due to optimized planar transformer layouts. Placing primary and secondary ground shields beneath the open-frame PCB further suppresses near-field coupling. For applications sensitive to B-field radiation, specifying an optional metal baseplate yields approximately 10 dB/µM additional magnetic field attenuation.

Uncontrolled inrush current charging input bulk capacitors can trigger bus voltage sags, trip upstream circuit breakers, weld relay contacts, or induce high-voltage inductive spikes that stress adjacent equipment. Active inrush limiters or hot-swap controllers mitigate peak current demands, ensuring smooth system power-up.

Complex digital processors demand strict turn-on/turn-off rail ordering. Common implementation strategies include:

• Optoisolated Enable Cascading: Drive secondary-side Power-Good outputs through optocouplers to trigger the primary-side ON/OFF pins of downstream converters in sequential order.
• Clamping Diode Arrays: Place Schottky diodes between voltage rails (e.g., 5V to 3.3V) to prevent rail potential differences from exceeding a single diode drop during power-up transients.
• Series MOSFET Ramp Controllers: Insert N-channel MOSFETs in series with outputs, controlling gate drive slew rates to ramp output voltages in strict adherence to timing profiles.

Regulated DC-DC converters act as constant power loads, causing input current to decrease as input voltage increases. This characteristic presents an incrementally negative input impedance at low frequencies. If the source impedance of the input EMI filter exceeds the converter's negative input impedance, control loop oscillations will occur. Integrating an aluminum electrolytic damping capacitor with optimized equivalent series resistance (ESR) across the converter input terminals stabilizes the input stage.

Output voltages are adjusted using external trim resistors. Connecting a resistor between the TRIM pin and -SENSE trims the output voltage down; connecting a resistor between the TRIM pin and +SENSE trims the output voltage up. Trim equations and resistor tables provided in datasheets conform to industry-standard brick configurations.

SynQor full-feature modules enable higher power delivery and N+1 redundancy by interconnecting dedicated control pins:

• Current Share (CSHARE): Interconnect CSHARE pins across all paralleled modules to actively balance output currents within 5%.
• Start Sync (CSYNC): Connect CSYNC pins to synchronize internal switching clocks and eliminate low-frequency beat oscillations.
• Sense Line Junction: Tie all +SENSE and -SENSE lines together at the precise load distribution point for accurate voltage regulation.

Open-frame and cased modules are ESD-sensitive electronics and must be stored in conductive totes adhering to ANSI/ESD S20.20 controls. SynQor products utilize no-clean flux systems exceeding Telcordia GR-78-CORE SIR standard requirements. Standard aqueous board washing processes are fully compatible; however, ensure adequate forced-air drying cycles to prevent moisture entrapment beneath baseplates.

Mean Time Between Failures (MTBF) is calculated in accordance with MIL-HDBK-217F and Telcordia SR-332 standards across varied temperature, airflow, and stress levels. SynQor continuously tracks Demonstrated Field Reliability from global defense and aerospace deployments, demonstrating MTBF values exceeding several million hours.

SynQor enforces a rigorous 3-stage release framework under AS9100 and ISO-9001 certified quality management systems:

• Proof of Design (POD): Highly Accelerated Life Testing (HALT), electrical stress verification, thermal imaging, and capacitive load capability analysis.
• Proof of Manufacturing (POM): Statistical process control (SPC) yield verification, automated optical inspection (AOI), and Design for Manufacturability (DFM) audits.
• Product Qualification: Full compliance testing against MIL-STD-810G (thermal shock, shock, vibration, humidity) and IPC-A-610 Class 3 assembly criteria.

UPS Lithium-Ion battery units exceeding 100 Whr are classified as Class 9 Fully Regulated Dangerous Goods. Battery packs must be detached from the main UPS chassis during transit and enclosed in UN-certified solids packaging (UN 3480/3481) with appropriate hazardous material labeling applied in compliance with 49 CFR and IATA regulations.

SynQor VITA 46.11-compliant 3U and 6U VPX power supplies support PMBus and IPMI I2C telemetry protocols. System controllers can monitor input voltage, input current, card-edge temperatures, and output rail status (VS1, VS2, VS3, 3.3Vaux). Active faults automatically assert the FAIL* signal low, prompting digital diagnostics across all rails.